The results of mathematical simulation, development and investigation of a modulator
with 4H SiC pin diodes are presented. We simulated the effect of bias modes on isolation and
transmission between the modulator input and output in the 1−20 GHz frequency range, for pin
diodes with 6 μm long i-region. It was calculated that the isolation in a modulator with three diodes
may run into –45 dB, the transmission losses being no more than 2 dB.
The modulator was made as an integrated circuit (IC) on the basis of nonsymmetrical strip lines
(characteristic impedance of 50 Ω) incorporating chips of high-voltage 4H SiC pin diodes with iregion
6 μm long, mesa diameter of 60 μm and calculated avalanche breakdown voltage of 1000 V.
We studied the experimental parameters of this modulator as a function of forward current and
reverse voltage in the 2.4−12 GHz frequency range, as well as the microwave signal switching
behavior. It was determined that the modulator is characterized by transmission losses of
1.0−2.0 dB and isolation of 27−34 dB (in the 2.4−7 GHz frequency range). The formation of
microwave pulses with leading (trailing) edge of 22 (29) ns was also observed.